The economics of processing shipping containers is volume directly proportional to the containers through a shipping yard. To enhance the flow of containers, certain apparatus has been developed whereby two containers may be moved at one time and so at least at this stage doubling the rate of movement of the containers.
For instance, where access to move containers is limited, it is particularly advantageous to use apparatus that will fit within a confined space, such as limited to a single head block and spreader, with apparatus that includes two head blocks and spreaders.
To this end it would be further advantageous if two head blocks could be used for two spreaders engaging two containers and further that the spreaders or head blocks could be separated so as to deal with the two containers as individuals rather than collectively.
A system has been proposed to achieve this involving arms projecting from one head block having ball shaped ends and mounted to a second head block is a mechanical device for engagement that comes together to grip the balls in a pincer-type action, creating a ball joint between the two devices. Thus by activating the arms to move to position and further to have the pincers to move into position also, the head blocks can be engaged and disengaged accordingly.
However, in order to engage the two head blocks, the tolerance for the pincers to engage the balls of the projecting arms is of the order of 50 mm. One can imagine two head blocks having spreaders attached thereto in an outdoor environment where wind can affect the motion of the spreaders. To engage the head blocks within a tolerance of 50 mm would be an extremely difficult activity and certainly time consuming detracting from the benefits offered by the dual head blocks.
Other more complex systems are known such as those having projecting arms formed from parallelogram linkages. Whilst useful said systems are more complex to manufacture and require a greater number of moving parts which could lead to further maintenance.
It would therefore be advantageous to have a head block that could be engaged and disengaged more easily than the above mentioned system.